1. Field of the Invention
The present invention relates to a method and an apparatus for adapting air values from a substitute performance graph, which is employed for controlling a mixture preparation during pulsations of air in an intake tube of an internal combustion engine, to currently prevailing state variables of the ambient air, such as temperature and pressure, for example.
Fuel measuring control systems require accurate information regarding an aspirated amount of air per stroke by the internal combustion engine for a correct mixture preparation. Such information is obtained through rapidly reacting air measuring devices which operate in accordance with the hot film principle. The output signal of the air meter follows each pulsation in the airflow in view of the high reaction speed.
Return flow air masses are also erroneously picked up. As soon as such pulsations occur, the air meter no longer provides correct measuring values which would be employable for the mixture preparation. If such pulsations are recognized, predetermined air values from a substitute performance graph are employed for the air mixture preparation, instead of the measuring values of the air meter. For example, such values are dependent on the load being stored, in particular the rotational speed and the throttle valve angle. The air values are established during normal temperature and normal pressure, tuned to the given type of engine, and stored in the substitute performance graph.
2. Summary of the Invention
It is accordingly an object of the invention to provide a method and an apparatus for adapting air values from a substitute performance graph, being employed for controlling a mixture preparation during pulsations of air in an intake tube of an internal combustion engine, to currently prevailing state variables of ambient air, which overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and apparatus of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, in a method for adapting air values from a substitute performance graph to currently prevailing variables of state of ambient air, the air values being used for controlling mixture preparation if pulsations of air occur in an intake tube of an internal combustion engine instead of using measured values supplied by an air meter, the improvement which comprises adapting the air values by multiplying the air values by an adaptation factor, and calculating the adaptation factor by dividing a measured value supplied by the air meter in the intake tube of the internal combustion engine by an air value taken from the substitute performance graph and subjecting the adaptation factor to sliding averaging, at times when no pulsations are present; and using a lambda-control-average value as the adaptation factor and subjecting the adaptation factor to sliding averaging, at times when pulsations are present.
With the objects of the invention in view, there is also provided, in a method for adapting air values from a substitute performance graph to currently prevailing variables of state of ambient air, the air values being used for controlling mixture preparation if pulsations of air occur in an intake tube of an internal combustion engine instead of using measured values supplied by an air meter, the improvement which comprises adapting the air values by multiplying the air values by an adaptation factor, and calculating the adaptation factor by taking a substitute air value from the substitute performance graph, multiplying the substitute air value by a temperature value, multiplying a reciprocal value of the multiplication by a measured value supplied by the air meter in the intake tube of the internal combustion engine to obtain a result, and subjecting the result to sliding averaging, at times when no pulsations are present; and using a lambda-control-average value as the adaptation factor and subjecting the adaptation factor to sliding averaging, at times when pulsations are present.
First of all, two operating ranges of the internal combustion engine are differentiated in the method according to the invention.